Morgan’s corner is one of my favorite vacuum form mold makers. It’s best to follower her facebook page instead of buying on etsy. She posts new molds there, and then she’ll send you an invoice on paypal.
Just Fairy Fizzies is on etsy and they have good VF molds too.
Jody Hansen Studios on etsy VF molds
Inedible Soaps on Etsy, 3D printed 3 piece molds, maybe VF too.